2 Using Semantic

You can begin using Semantic by enabling Semantic mode, a global
minor mode: type M-x semantic-mode, or open the ‘Tools’
menu and click on the menu item named ‘Source Code Parsers
(Semantic)’. See Semantic mode.

When Semantic mode is turned on, Emacs automatically parses each file
you visit. You can then use Semantic user commands in those
buffers (see Semantic mode user commands). You can also choose to
enable a number of “helper” minor modes for saving tags, displaying
tag information, and so forth.

To enable Semantic mode each time you start Emacs, add the line
(semantic-mode 1) to your initialization file. See Init
File in Emacs manual.